PSEB 9th Class SST Notes Geography Chapter 4 Climate

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This PSEB 9th Class Social Science Notes Geography Chapter 4 Climate will help you in revision during exams.

PSEB 9th Class Social Science Notes Geography Chapter 4 Climate

Climate:

  • Climate is the sum total of weather conditions over a large area for a long period of time.
  • There are many climatic conditions in India.

Factors influencing climate:

  • Many factors affect the climate of a place such as distance from the equator, distance from the sea, altitude of a place, impact of winds, relief effect, jet streams, etc.
  • The Indian Climate is almost the same due to its physical structure.

Rainfall:

  • Rainfall is a type of precipitation when moisture falls on the earth in the form of drops of water.
  • It is of three types: Convectional rainfall, Orographic rainfall, and Cyclonic rainfall.

PSEB 9th Class SST Notes Geography Chapter 4 Climate

Meaning of Monsoon:

  • The word ‘Monsoon’ is said to be derived from the Arabic word ‘Mausim’ meaning season.
  • In this way, monsoon is a season in which wind changes its direction with the season.

Monsoon System:

  • The monsoons are experienced in the tropical area roughly between 20°N and 20°S.
  • It is created due to the opposite position of air pressure.
  • This position of air pressure changes continuously.
  • That’s why in different seasons, the situation of winds changes on either side of the Tropic of Cancer.
  • Except this, jet streams also play an important role in the mechanism of the monsoon.

Seasons in India:
In the annual season of India, there are four major seasons-winter seasons, summer season, advancing monsoon, and retreating monsoon.

Winter Season:

  • There is a winter season in almost the whole of India from December till February.
  • In this season, north-eastern trade winds blow over the whole country.
  • In this season, temperature decreases when we move from south to north.
  • It is a dry season but some amount of rainfall occurs on the Tamil Nadu coast from these winds as here they blow from sea to land.

Summer Season:

  • This season remains from March to May.
  • In March, the highest temperature is about 38° Celsius, recorded in the Deccan plateau.
  • Gradually, low-pressure area starts to move towards North India which experiences high temperatures.
  • In the north, these low-pressure winds are called loo, Kaal Baisakhi in West Bengal, and Mango shower in the coastal areas of Karnataka.

Advancing Monsoon:

  • This season remains from June to September.
  • South-West monsoon enters India through two branches-Arabian sea branch and the Bay of Bengal branch.
  • These winds give a lot of rainfall to the country.
  • North-East India experiences lots of rain but the North-West part of India remains dry.
  • The months of July and August experience almost 75% to 90% rainfall in the country.
  • Mawsynram, a place in the Garo and Khasi hills of North-East India, experiences the highest rainfall in the world.
  • The second place is of Cherapunji.
  • Western Ghats of South India experiences heavy rainfall due to monsoon winds coming from the Arabian Sea branch.

PSEB 9th Class SST Notes Geography Chapter 4 Climate

Retreating Monsoon:

  • During the months of October and November, the monsoon over the northern plains becomes weaker.
  • This is replaced by a high-pressure system.
  • The retreat of the monsoon is marked by clear skies and a rise in temperature.
  • Due to high temperature and humidity, the weather become rather oppressive.
  • This is commonly known as ‘October heat’.
  • On the coast of the southern plateau, cyclones create havoc and are often very destructive.

Distribution of Rain:

  • Parts of the western coast and north-eastern India receive over about 300 cm of rainfall annually.
  • But western Rajasthan and adjoining parts of Gujarat, Haryana, and Punjab receive less than 50 cm of annual rainfall.
  • Higher parts of the country (Himalayan region) receive snowfall.
  • The annual rainfall is highly variable from year to year.
  • Variability of monsoon brings flood in many parts and drought in the other parts.

Instruments for climate:

  • Many instruments are used to measure different climatic features such as Maximum and Minimum Thermometer, Android Barometer, Dry and Wet Bulb Thermometer, Rain Gauge, Anemometer, Wind wane, etc.

PSEB 9th Class SST Notes Geography Chapter 4 Climate

Natural Disasters:

  • Nature is all-powerful.
  • When any natural calamity occurs, it leads to the great loss of life and property.
  • Tsunami was one of the natural disasters which came in many countries of South Asia in December 2004.
  • It led to the death of thousands of people and the destruction of property as well.

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